Many people are nervous about bacteria. Are all bacteria bad and unhealthy? Why or why not?

A. No. Humans have an average of 100 trillion bacteria cells living in and on each one of us called microbiome, which is essential for health. They digest food, develop immune systems, and protect us from disease. Other types of bacteria though, can be dangerous.

B. No. Bacteria is only unhealthy if it gets inside you. The skin forms a protective barrier that prevents bacteria from getting inside, but if it does it always leads to sickness or disease.

C. Yes. Bacteria called microbiome is dangerous bacteria that can get on human skin and in the gut. Microbiome is a unicellular organism that is too small to see, so we must be cautious not to get it inside the body or it can cause sickness and disease.

D. Yes. All bacteria, even a single bacteria cell is dangerous.